.container{
    display:grid;
    grid-template-rows:repeat(3,1fr);
    grid-template-columns:repeat(3,1fr);
    place-items: center center;
    width: 300px;
    height: 300px;
    border:1px solid;
}


.item{
    border: 1px solid red;
    width:50px;
    height: 50px;
}